Knob Coral

About

Knob Coral (Dipsastraea maritima) is a large polyp stony coral with a distinctively textured surface. The raised, rounded corallites that give it its common name create a bumpy, almost cobblestone appearance across the colony. Found across a wide Indo-Pacific and broader tropical range, it typically grows on reef slopes and flats where light and water movement are moderate rather than extreme. In the aquarium, it tends to be a solid, undemanding presence compared to some of the flashier LPS corals, though it still calls for someone who has a handle on stable water chemistry and consistent maintenance. This is not a beginner's first coral, but it is not a specialist-only species either. Its growth form can be encrusting to mounding depending on conditions, and colonies can develop into genuinely impressive structures over time with patient care. Dipsastraea corals as a genus are known for being reasonably tolerant of minor fluctuations compared to more delicate LPS, which makes this a sensible choice once you have moved past the initial learning curve of reef keeping. Give it moderate flow to keep detritus from settling on the tissue and enough light to support its zooxanthellae, and it will reward you with steady, healthy growth.